Question

6.(b) If x + y =5 and 4xy = 21, find x³ + y³

please give me the correct answer step by step guys I follow u​

Answer 1

Step-by-step explanation:

x+y = 5, 4xy = 21 => xy = 21/4

to find x³ + y³

(x+y)³ = x³ + y³ + 3xy(x + y)

5³ = x³ + y³ + 3*21/4 ( 5 )

125 = x³ + y³ + 63/4*5

x³ + y³ = 125 - 63/4*5

x³ + y³ = 125 - 12.6 × 4

x³ + y³ = 125 - 50.4

therefore x³ + y³ = 74.6